Frangible hydrant



July 22, 1941 i A V D. F. O'BRIEN 2,249,848r

FRANGIBLE HYDRANT Filed June 22, 1959 Patented July 22, 1941 UNITED STATES PATENT oiFFlcs 2,249,848 FRANGIBLE HYDRANT` Denis F. OBrien, East Orange, N. J.

Application June 22, 1939, Serial No. 280,478

z claims. (o1. 2cv-ics) Y Thisl invention relates to improvements in re hydrants and more particularly in frangible couplings for valvestems.

1t is an object of the invention to provide couplings of great strength under service conditions, but which are readily fracturable under impact heavy enough to threaten damage to a hydrant.

It is a further object: to, provide couplings which are inexpensive to manufacture and are replaceable when broken with a minimum amount of labor and delay.

Withl the foregoing objects and others which will appear in the following full description in mind, the invention consists in the combinations and arrangements of parts and details of construction which will now be fully describedin connection with the accompanying drawing and then pointed out more particularly in the appended claims.

In the drawing: Y

Fig. 1 is a side view partly in elevation, and partly in vertical section, of a hydrant embodying the invention in a preferred form;

Fig. 2 is a horizontal section, on` the line 2 2 of Fig. 1 as. to the hydrant casing but through a groove located. near the middle of the valve stem coupling, and on an enlarged scale;

Fig. 3 is a vertical section taken on the line 3--3 of Fig. 2 andy further enlarged; and

Fig. 4 is an. enlarged fragmentary view showing the valve stem coupling of Fig 1.

Referring to Fig. 1 showing the general construction of the hydrant, the hydrantcasing is composed of an upper section I resting upon. a lower section 2. which. in turn-r is attached to a valve casing 3` connected at 4 to a main (not shown.) in the usualy way. The hydrant is provided' with4 the usual fitting 5 for attachment of a hose and is surmounted by ahead 6 with the usual nut 'I for opening and closing the valve. The valve stem` is composed of two sections 8 and 9 joined by the coupling lil, later to be described in detail, and. loweredn 'and raised by means of the nut 'I through screw mechanism .Y

of any usual type (not shown) to operate the valve I I which seats upwardly against valve seat I2. Casing sections I and 2 are separated by a gasket I3 to reduce leakage and held together in alinement` by a coupling I4. The present inven- I.,

tion consists particularly in theconstruction of the valve stem coupling III and in the way in which this partis rendered frangible. Those features of the construction relating to the casing coupling specifically and, more broadly to I both the casing coupling and the Valve stem coupling are claimed in my copending application Serial No. 308,945, led December 13, 1939, and being a division of the present application which is directed more particularly to the features of the invention relating to valve stem coupling. Asshown in Figs. 1, 2 and 3, the casingsections I and. 2 are formed with shoulders I5 and I6 near their ends and forming generally horizontal annular surfaces for engagement by coupling I4. 'Ihe coupling I'4 is composed of two parts I 1 and I8 held together by screws I9 and provided with inner surfaces 25: and 2| to engage the surfaces I5 and I6 respectively.

As best' shown inFigs. 2 and 3, the casing section ends beyond shoulders I5 and I6, are of generally cylindrical form and the coupling I4 is hollowed` out to accommodate a sealing member 22 made of flexible material such as rubber and having vthe form of a continuous tire with inturned flanges 23. As vwill be readily understood,jany water escaping past washer I3 will tend to force the flanges 23 against the casing Vends providing an extremely tight seal'.

Coupling I4 is rendered frangible by forming the metal' below surface 2| 'into a flange of the desired thickness, as by formingthe members- I1 and I8 with a groove or recessV 24', as shown. It wille-be understood that surfaces I5, I6, 2B and ZI arefinished to provide proper engagement between coupling I4 and the casing sections I and 2. The coupling sections are preferably formed by casting, however, and preferably made Y of such material as cast iron, which has desirable .characteristics of strength under steady stresses together with liability to fracture under undue impact or sudden stress. Asis evident,- impact of a vehicle against the upper casing section I is communicated to the metal below surface 2t as a shear, substantially in alinement with the outersurface of the end of' casing section 2. Moreover, any force tending to rock the casing section I will be borne initiallyby one side only ofthe surface 2 I, rendering fracture of this member under collision relatively easy Vand insuring breaking of the couplingbefore any. possible damage to the hydrant section can occur.

i `The frangible casing couplingV combinedwith the seal external to the hydrant casing and. constituting the ,particular casinglcoupling and Seal by means of which thecasingis rendered fran`` gible toV produce fracture of the valve stem coupling is claimed in my above-mentioned divisional application, but its operationais described in the present case for completeness of illustration.

It has previously been proposed to employ frangible couplings capacitated to draw the hydrant casing sections together, either by means of bolts or right and left hand threading in the coupling itself, the hydrant -being sealed solely by means of a gasket or the like. This practice requires, however, considerable pressurebetween the casing sections to -prevent leakage, and the frangible couplings are subjected to correspondingly heavy stresses. In addition, the couplings are required to withstand abuse resulting from over-tightening by the workmen of the screw mechanisms provided for tightening the coupling.

As a` result, it has been found that prior art A' couplings show a definite tendency to fail to break under impact sufficient vto damage a hydrant, when made strong enough to produce a proper seal.

'Ihe coupling of the invention, however,V is required in service, to withstand only the tension produced by water pressure within the casing.

-For example, the coupling surfaces and 2l may be separated by a distance somewhat greater than .that between the shoulders I5 and I6 on the casing sections when the latter are separated by a given gasket I3, a perfect seal being still provided by the ring 22. Under these conditions, as is apparent, the frangible 'coupling is required in service to withstand only the ten- Ysion produced by'water pressure withinth'e hydrant, and it becomes possible to construct the coupling so asto insure breakage under impact of a dangerous magnitude without creating any liability to failure under service conditions.

The valvestem coupling I Il comprises a body member formed with oppositely facing sockets 26 -and 21 to receive the valve stem sections 8 and 9. 'These sections are attached to theV coupling I0 by means of pins 28 passing through the-m and vthrough the walls of sockets 26 and 2l.` At the` level of the pins 28 Vcoupling I Il is 'provided with shallowgrooves 29 receiving split spring hoops 30 which serve to hold the pins 28'in place, 'as' bestV shown in Figs. 2 and 4.

A s shown in'Fig. 4, vsocketsZ and 21 are cast with enlargements 3| at their inner ends,ewhich facilitatev finishing of ,their walls to t 'Valve stem sections 8 and 9. AThese sections may rest 'Y on the metal of coupling I0 separating sockets Zevand 2l, or not, it being unimportant in the present;A construction whether they do so.

To ensure vfracture of the coupling IIJ when collision occurs,'it is formed with an encircling greove 32, located close .to one of the enlargemerits 3| in the axial direction and substantially inalinement with its outer edge; as shown in Fig. 4L YThefcoupling I0, similarly tok coupling I4, is preferably'madeuoiA castV iron, the only finishing required being` that Y'of the wallswof sockets'Y 2B aindfl` `whichV engageY theY valve stem@ sections 8.andn9, anddrilling holes for. pins 228.

Y Infthis1coupling,,asin the hydrant casing couplingpreviously described, ,impact against hy- @iwnt cameretta'. is. transmitted to .the frangibleportion ofthe .coupling between enlargement 3 IV and groove 3 2'as a shear and in this case lalso the formation ',of the coupling by castingA produces crystallization tending to predisposetp `fracture between'the lower edge `of the enlargement 3| and the groove32. ,ZWhencQllision occurs, rocking hydrant. section I on hydrant section 2, the outer coupling I4 breaks and the inner valve stem coupling I0 breaks instantaneously thereafter, permitting the upper half of the hydrant, together with valve stem section 8, to fall off the lower half. The valve II remains closed, or, in fact, will close immediately if open at the time of collision, due to water pressure within the casing 3. The repair of the hydrant after collision, according to theV present invention, is extremely simple and involves only the following steps: A new coupling Ill is placed upon the lower valve stem section 9 and pin 28 and hoop 30 placed in position upon it. Valve stem section 8 is then inserted in the upper socket 26 and similarly secured in position. Sealing ring 22 may now be placed over section I or 2 and the former placed upon the latter. The ring is now pulled into position and a new pair of members I'I and I8 placed around it and fastened together with screws I9. At this point .the operating structure of the usual type (not shown) is put in position and the head 6 of the hydrant fastened to it, completing the repair.

Among the advantages of the present invention, in addition to simplicity in use and manufacture, is the great strength of the couplings under service stresses together withra certainty of breakage under relatively slight impact, which insures protection of the hydrant'l itself. For example, with the present invention it has been found possible in a hydrant of Iten inch diameter to construct the parts so that the outer coupling will withstand water pressures in excess of six hundred pounds per square inch, producing a tension on the coupling of the order of twenty to twenty-live tons, and yet have the coupling invariably break immediately upon collision with the hydrant of even a small baggage truck weighing a few hundred pounds and moving at little more than walking speed. In theV case of the valve stem coupling it has been found DOssible to construct this member so as to withstand tension well in excess of five tons land at the same time to fracture upon impact against the valve stern, under test conditions, of a six pound weight dropping from a height of only two or three feet. As is apparent, the invention accordingly provides for ampleV factors .of safety, both in the withstanding of service loads and in the protection of the hydrant against damage by collision. A What is claimed is:

1. A frangible coupling for hydrant valve stems comprising a member having oppositely facing socketsrfor engaging a pair of alined valve stem sections and a circumferential groove around said member extending radially inwardl thereof to substantial axial `alinement withcthe-,bore of one of said sockets and spaced axially therefrom to dene a frangible portion of thickness such as to carry service vstresses and fracture under Y impact suiiicient to damage a' hydrant.

2. A coupling according to claim l in which the material of the said coupling has a crystal structure extending through said frangible portion between saidr last mentioned socket and Vsaid groove of the vcharacter produced by a 4casting operation without substantial iilleting, whereby said ycoupling is predisposed to fracture in a predetermined zone in said frangible portion.

DENIS F. OBRIEN. 

